One of the biggest reasons why the Eagles have gotten worse and worse over the past four seasons is the absence of legendary defensive coordinator Jim Johnson, who died from cancer during the 2009 offseason.

Replacing Johnson was Sean McDermott, a great guy, but not a great defensive coordinator. The Eagles allowed 289 points in Johnson’s final season, in 2008. That number jumped to 337 in 2009 and 377 in 2010.

Yes, the Eagles didn’t have Brian Dawkins in 2009 or 2010, but that doesn’t excuse the defensive struggles. McDermott was predictably fired after the 2010 season, and a quest for a new defensive coordinator began.

The Eagles reportedly interviewed dozens of candidates. Dozens.

After a very long process, the Eagles finally made their decision for defensive coordinator.

I’ll never forget getting a text from philly.com that the Eagles had selected Juan Castillo as their defensive coordinator. Knowing that Castillo had been our offensive line coach for more than a decade, I immediately texted my brother and dad that philly.com had messed up.

Then I got several more texts confirming the news, and my heart sunk.

The Eagles chose a man who had never coached defense at any level in the NFL, or in the last two-plus decades, to lead their defense in a pretty important 2011 season for the future of the head coach.

As expected, the Eagles’ defense struggled in 2011, especially at the beginning of the season. They blew a fourth quarter lead in week two against the Atlanta Falcons, in week three against the New York Giants, in week four against the San Francisco 49ers, in week nine against the Chicago Bears, and in week 10 against the Arizona Cardinals.

They allowed a 47-yard touchdown run to Rams’ running back Steven Jackson on the season’s first play, and they allowed a 15-yard touchdown run to Seahawks’ running back Marshawn Lynch that ranks among the greatest runs I have ever seen.

There were a number of players, such as middle linebacker Casey Matthews and safety Jarrad Page, who should not even have been on the team, let alone in a starting spot.

There were also players like Nnamdi Asomugha and Dominique Rodgers-Cromartie, who weren’t being used in the system that they are most comfortable with.

And the famed wide-nine defense that was supposed to help the Eagles tremendously in 2011 got shredded in the run game, week after week after week.

Things got so bad that rumors started to circulate that Castillo wouldn’t last the season, and if he did, that a defensive consultant would have to be brought in to help.

Things started to turn around in the season’s final four games, when the Eagles beat up on the Miami Dolphins, New York Jets, Dallas Cowboys, and Washington Redskins. The Eagles allowed just 46 points in those four games, an average of 11.5 points per game.

But the Eagles missed the playoffs after a very disappointing 8-8 finish, and although the defense allowed 328 points, 49 fewer than the previous season, Castillo did not impress in his first season as the team’s coordinator.

Incredibly, or should I say predictably, Andy Reid chose to retain Castillo for the 2012 season, which now stands as a do-or-die season for the Philadelphia Eagles’ head coach.